Prevention of spinal cord injury during thoracic spine surgery

描述（由申请人提供）：涉及胸椎的手术有时需要植入金属棒来稳定和融合椎体。一种越来越流行的固定这些椎体棒的方法是通过椎弓根放置大型骨螺钉，将每个椎体的“后”部分（即椎板）与“前”部分（即身体）连接起来，然后将椎体棒与植入的螺钉连接起来。通常将一个狭窄的“锥子”（或椎弓根探测仪）强行穿过椎弓根（形成椎弓根轨迹），然后沿着这个轨迹放置一颗螺钉。理想情况下，螺钉应完全包含在骨内，但如果在胸椎内的任何水平向中线（即内侧）“脱臼”，则可能撞击并损伤脊髓。本研究的目的是开发一种新的术中脊髓传导监测（IOM）试验，以预防胸椎弓根螺钉内侧移位，从而预防脊髓损伤。在2个具体目标的第一个中，我们将建立通过椎弓根轨道电刺激脊髓和神经根所需的能量（即在螺钉植入之前）与螺钉放置后相对于椎弓根的位置之间的关系。我们预计，穿过内侧椎弓根壁骨的椎弓根轨迹将导致弱电流强度的脊髓刺激。我们将回顾性地制定规则，告诉我们何时在特定椎弓根轨道内放置螺钉是安全的。在具体目标#2中，我们将前瞻性地应用这些规则，以积极预防新患者手术期间螺钉错位。此外，我们将这些受试者随机分为两个队列。在一组中，我们将在外科医生做椎弓根轨迹时，通过改良的椎弓根探测仪积极刺激，如果需要改变椎弓根轨迹的方向，我们将向外科医生提供即时反馈。我们预计，在特定目标#2中研究的受试者中，与使用特定目标#1的方案进行测试的受试者相比，胸椎弓根螺钉中间错位的病例将会减少。此外，我们预计那些通过椎弓根寻找器接受主动刺激的受试者在所有受试者中内侧螺钉错位的发生率最低。在本研究结束时，我们将开发并验证一种新的胸椎弓根螺钉置入术中监测方法。这项试验不仅可以降低脊髓损伤的风险，而且还可以减少需要额外手术来修改螺钉放置的受试者数量，“虽然本身不会造成脊髓损伤”，但仍会侵犯椎管空间，如果保留原位，最终会导致症状。公共卫生相关性：胸椎治疗畸形或创伤的手术使脊髓处于相对较高的损伤风险，特别是在脊柱椎弓根植入螺钉时。本项目将开发一种新的方法来防止意外螺钉置入脊髓，从而防止脊髓损伤。

DESCRIPTION (provided by applicant): Surgery involving the thoracic spine sometimes requires the implantation of metal rods to stabilize and fuse the vertebrae. One increasingly-popular method of anchoring these rods is to place large bone screws through the pedicles that connect the `back' part of each vertebra (i.e. the lamina) with its `front' part (i.e. the body), and then connecting the rods to these implanted screws. Typically a narrow `awl' (or pedicle finder) is forced through the pedicle (creating the pedicle track), and then a screw is placed along this track. Ideally the screw should be fully- contained within bone, but if it `misses' towards the midline (i.e. medially) at any level within the thoracic spine, it may hit and injure the spinal cord. The goal of this study is to develop a new intra-operative monitoring (IOM) test of spinal cord conduction to prevent medial malplacement of thoracic pedicle screws, thereby preventing spinal cord injury. In the first of 2 Specific Aims, we will establish the relationship between the amount of energy needed to electrically stimulate spinal cord and nerve roots through the pedicle track (i.e. prior to screw implantation) and the position of that screw relative to the pedicle, once the screw is placed. We anticipate that pedicle tracks which have broken through the bone of the medial pedicle wall will lead to spinal cord stimulation with weak current intensities. We will retrospectively develop rules to tell us when it is safe to put a screw in a particular pedicle track. In Specific Aim #2, we will apply these rules in a prospective manner to actively prevent screw malplacement during surgery in new subjects. Moreover, we will randomize these subjects into two cohorts. In one group we will actively stimulate through a modified pedicle finder while the surgeon is making a pedicle track, to provide immediate feedback to the surgeon if the orientation of the pedicle track needs to change. We anticipate that there will be fewer cases of medially-malplaced thoracic pedicle screws in subjects studied in Specific Aim #2 compared to those tested with the protocol from Specific Aim #1. Moreover we expect that those subjects who receive active stimulation through the pedicle finder will have the lowest incidence of medial screw malplacement of all subjects tested. By the end of this study period, we will have developed and validated a novel form of intra- operative monitoring for thoracic pedicle screw placement. Not only will this test lower the risk of spinal cord injury, but it will also lower the numbers of subjects who require additional surgery to revise screw placements that " while not causing spinal cord injury per se" are still encroaching upon the canal space enough that they would eventually lead to symptoms if left in place. PUBLIC HEALTH RELEVANCE: Surgery to the thoracic spine to treat deformity or trauma places the spinal cord at relatively high risk for injury, particularly when screws are implanted into the pedicles of the spine. This project will develop a novel method to prevent accidental screw placement into the spinal cord, thereby preventing spinal cord injury.